1. Field of the Invention
This invention relates to a syringe having an inner cannula integral with the distal portion of said syringe and a piston sealably engaging said inner cannula with said piston integral with a plunger-conduit system. The inner cannula is integral with the distal portion of the syringe and positioned therein so as to allow a fluid to flow around said inner cannula and into the barrel of the syringe when said piston is advanced proximally and in so doing, this first obtained fluid is separate from a second fluid which can be obtained by inserting a vacuum glass tube into a fluid collection receptacle attached to the plunger conduit system. After a plurality of vacuum tubes are filled with the second obtained fluid, the first obtained fluid can be returned to the patient by simply advancing the piston distally.
2. Information Disclosure Statement
Since the advent of the Acquired Immune Deficiency Syndrome (AIDS), many disposable devices have been developed to prevent accidental needle sticks. However, prior art lacks simplicity and blood drawing procedures found traditionally cumbersome are now made unusually complex. Yet even further, as cost containment becomes more important, the additional blood drawing components found in prior art touted as being safe are now realized to be unusually complex, not universally applicable, and consequently not cost worthy.
Often, severely ill patients in the hospital will require central venous catheterization for administration of various medicinal preparations and arterial catheterization for monitoring of blood pressure.
Regarding central venous catheterization, often a triple lumen catheter will be placed in the patient's subclavian vein and at least one lumen of the catheter is used for the administration of fluid; the two remaining unused lumens may be used to draw blood for laboratory testing or alternately the administration of a variety of other medicinal preparations. If a given lumen of the central venous catheter is used to obtain a blood sample for laboratory testing, a syringe is attached to the unused lumen and this first obtained venous blood considered too dilute for laboratory testing is drawn into the barrel of the syringe, the syringe is then detached and discarded. A second syringe is then attached to this lumen and a second obtained volume of venous blood is drawn into the barrel of the syringe. The volume of venous blood obtained is limited by the volume of the syringe. This second obtained venous blood is then transferred to vacuum glass tubes by cumbersome traditional methods.
Regarding arterial catheterization, an arterial catheter is inserted into the patient's radial artery. The now inserted arterial catheter can then be attached to a blood pressure monitor. The connection to the blood pressure monitor is established with pressure tubing having at least one three-way valve proximal to the catheter insertion site. When monitoring blood pressure, heparinized solution fills the pressure tubing to the level of the catheter insertion site distally and a pressure transducer proximally. In the monitoring mode, the three-way valve is patent with the distal catheter and the proximal pressure transducer. Simultaneously, the three-way valve is closed to a blood sampling side port used to obtain blood samples for laboratory testing. To obtain blood for laboratory testing, the three-way valve is closed toward the proximal pressure transducer and patent toward the distal catheter and the blood sampling side port. Thereafter, a syringe is attached to the blood sampling side port and a first obtained volume of arterial blood considered too dilute for laboratory testing is drawn into the barrel of the syringe and the syringe is then detached. A second syringe is then attached to the blood sampling side port and a second obtained volume of arterial blood is drawn into the barrel of the syringe. This second obtained volume of arterial blood considered appropriate for laboratory testing is transferred to vacuum glass tubes in a traditional manner found to be cumbersome and unusually complex by those familiar with prior art. The three-way valve is then positioned to make patent the arterial catheter distally and the pressure transducer proximally so that the patient's blood pressure can be continuously monitored.
In view of the aforementioned cumbersome manipulations and unusually complex devices used to obtain a single sample of venous or arterial blood from an indwelling catheter, the objectives of the present invention are set forth and described herein.
In preparation for this application, a search was completed in Class 604, Subclass 231 and 187, Class 128, Subclass 214.4. In contradistinction to the patent application at hand U.S. Pat. No. 4,274,408 of Nimrod teaches a displaceable feeder tube contained within a syringe barrel having a function readily distinguishable from that which follows.